With continuous development of electronic design technology, the miniaturization level of electronic components and the integration level of integrated circuits are increasingly improved. Thus, heat flux density of the electronic components and assemblies is increased, which puts forwards a higher requirement for heat dissipation of the electronic components, and in turn a heat sinking pad arranged on the printed circuit board (hereinafter referred to as PCB) is required to have higher heat dissipation efficiency.
FIG. 1 is a structural schematic diagram of an existing PCB substrate. As shown in FIG. 1, a heat sinking pad 1 is arranged on the PCB substrate. A cross-shaped green oil solder mask 2 is arranged on the heat sinking pad 1, and divides the heat sinking pad into four soldering areas. The four soldering areas serve as tinning areas, and are coated with tin paste on the surfaces thereof. The heat sinking pad 1 is provided with a plurality of heat dissipation holes (not shown in the figure) at the areas underneath the green oil solder mask 2, for dissipating heat produced by electronic components on the heat sinking pad 1.
In the above heat sinking pad, the heat dissipation holes are formed at the areas underneath the green oil solder mask without being provided below the tinning areas, in order to prevent the tin paste from leaking through the heat dissipation holes. Thus, the heat produced by the electronic components soldered on the heat sinking pad 1 during working cannot be directly dissipated into the heat dissipation holes and discharged through the walls of the heat dissipation holes, so that the heat dissipation of the heat sinking pad is relatively slow and the heat dissipation efficiency is relatively low.